1. The Field of the Invention
The present invention relates to the field of matrix bands for use in dental procedures. More particularly, the present invention relates to anatomically contoured matrix bands for providing form for molding a dental filling into a shape that more closely approximates the anatomical shape of a tooth.
2. The Prior State of the Art
The filling of cavities is one of the most common dental procedures. In order to treat cavities the dental practitioner removes the infected portion of the tooth so as to form a hollow and then deposits a filling material, such as a composite, a resinous material, or an amalgam, into the tooth hollow.
During the dental filling procedure, a matrix band is typically wrapped around the side of the tooth to approximately define the desired shape of the finished tooth and to keep the filling material from flowing beyond the desired tooth boundary. A matrix band typically comprises a thin metallic or plastic strip that is flexible and can be bent around the tooth being restored. The matrix band is particularly useful because it provides form for the desired shape of the resultant filling. However, if the matrix band is not properly held in place then too much or too little filling material may be deposited into the tooth preparation, thereby distorting the configuration of the restored tooth.
An improper filling can lead to dental discomfort, misaligned teeth, capture of food particles, infections, and other dental problems. To avoid these problems, and to fix a distorted dental filling, it may be necessary to grind or drill the filling material down to the proper shape. However, it is desirable to avoid this process because it increases the time and cost of performing the filling procedure and can create anxiety and discomfort for the patient. Accordingly, it is desirable to place the matrix band against the tooth in such a way as to approximate the desired shape of the restored tooth so as to minimize the amount of post-filling shaping of the tooth restoration.
One problem with existing matrix bands, however, is that they do not naturally assume and conform to the anatomical shape of the tooth. In other words, they only grossly approximate the asymmetric contours of a tooth. Moreover, while flexible and deformable, non-anatomically configured matrix bands do not readily conform to the anatomically correct shape of the tooth being treated, particularly where a hollow exists.
Once the matrix band is placed into the desired placement, it is typically held in place with small dental wedges and/or one or more matrix band retainers. Even though such external devices provide some retention and conformation of the matrix band, non-anatomical matrix bands have the tendency to deform and/or slip out of the desired position.
If the matrix band slips out of its proper orientation during the filling procedure, the dental restoration can be distorted, thereby requiring additional shaping and potentially causing additional discomfort to the patient. It may also be dangerous for the matrix band to slip out of position during the filling procedure. For example, the matrix band can potentially get aspirated, lodged the patient""s throat, or scrape against sensitive mouth tissue, causing additional discomfort to the patient.
When restoring a tooth, it is important to form the contact point between the restored tooth and the adjacent tooth (or teeth) at the anatomically correct location, which is approximately two thirds of the way up from the gingiva to the top of the tooth. If the contact point is placed to low or too high then the tooth and adjacent teeth can become misaligned. This can also lead to other problems such as discomfort, capture of food particles, infections, and the like. Accordingly, it is desirable to provide a form that molds the contact point of the restored tooth at the anatomically correct location.
One problem with existing matrix bands, however, is that they often form the contact point too low. The reason for this is that they are symmetrically curved and consequently mold the dental filling with the contact point centrally disposed between the top and bottom edges of the matrix band and tooth, failing to accommodate for the generally trapezoidal shape of the tooth.
Accordingly, there is currently a need in the art for an improved matrix band that conforms to the asymmetrical and generally trapezoidal shape of teeth.
The present invention is directed to anatomically contoured matrix bands for providing an appropriate form for molding dental fillings into a shape that closely approximates the desired shape of the restored tooth and for molding the resultant filling with a contact point that is located in the anatomically correct location.
The matrix band of the invention comprises a thin strip of metal or plastic comprising two curves, a longitudinal curve that is substantially symmetrical (i.e., has a single radius of curvature) and a latitudinal curve that has at least two different radii of curvature. The longitudinal curve symmetrically extends from a first end of the matrix band to an opposite end of the matrix band. The latitudinal curve asymmetrically extends from a top edge of the matrix band to a bottom edge of the matrix band.
In a preferred embodiment, the shape of the latitudinal curve is defined by a first radius of curvature and a second radius of curvature. The first radius of curvature applies generally to the upper ⅓ of the matrix band and the second radius of curvature applies generally to the lower ⅔ of the matrix band. The magnitude of the first radius of curvature is significantly less than that of the second radius. In a preferred embodiment, the first radius is approximately one third the magnitude of the second radius.
In another embodiment, a flange extends from the bottom edge of the matrix band and has a third radius of curvature. The third radius preferably curves in a direction opposite to the direction of the first and second radius. The magnitude of the third radius of curvature is preferably approximately twice the magnitude of the first radius.
The different curvatures of the matrix band proportionately approximate the anatomical shape of one or more typically-sized teeth such that when the matrix band is disposed about an appropriate tooth receiving a dental filing, the matrix band is able to substantially conform to the asymmetrical, and generally trapezoidal, shape of the original tooth in both the horizontal and vertical directions.
One benefit of the invention is that it generally minimizes the amount of shaping that is required to complete the restoration of a tooth because it is able to mold the dental filling of the restored tooth into a shape that closely approximates the correct anatomy of the original tooth. The matrix band also molds the dental filling so as to have a contact point with one or both adjacent teeth in the anatomically correct location on the restored tooth. Additionally, because the matrix band of the invention conforms to the asymmetrical contours of a tooth, it is easily placed and held in proper placement against the tooth during dental filling procedures.
These and other features and advantages of the present invention will become more fully apparent from the following description and appended claims, or may be learned by practicing the invention as set forth below.